International tennis star Gabriela "Gaby" Sabatini was scheduled to be the last of 80 torchbearers to carry the sacred flame in the Argentine capital.
Argentine soccer legend Diego Maradona, initially planned as the first torchbearer, missed the run because of a conflicting personal schedule.
"I'm very proud (as a torchbearer), maybe because I know how important the Olympic Games are," five-time Olympian cyclist Juan Curuchet, who is competing for his sixth time - the most number of times for a cyclist - in Beijing this summer, said.
"It's the simple fact of being there that's important," he said.
The 77th torchbearer will be 77-year-old former soccer player Gong Jinyuan, now working as an expert on bone injuries in Buenos Aires, who still plays soccer every week.
"It's wonderful," Gong, who is from Sichuan province, said.
"It's like a dream for me, an ordinary person, to carry the sacred Olympic flame, especially in this nation of soccer," he said.
Since being lit in Athens, Greece on March 24 and officially launched on its global relay in Beijing a week later, the flame has traveled to Almaty, Istanbul, Saint Petersburg, London, Paris and San Francisco.
Here, in the second-ever Latin American Olympic torch relay city after Rio de Janeiro of Brazil in 2004 and the only Spanish-speaking city along its way to the Games in Beijing, the torch was carried from Constanera Sur to the Equine Club through beautiful boulevards and scenic spots, including the Plaza de Mayo and Avenida 9 de Julio, widely acknowledged as the world's widest street, with the iconic Obelisco at its center.
Following a celebratory ceremony at the Equine Club, the relay will depart before midnight local time and be transported to Tanzania's Dar Es Salaam.
"The visit of the Olympic torch in Buenos Aires is a one-time event in the sports history of our country," Francisco Irarrazaval, sports undersecretary of the Autonomous City of Buenos Aires, said.
"We are very proud to have the opportunity to host an event of such magnitude, united by important human values that we want to reflect on our society, through the universal slogan of 'Light the Passion, Share the Dream'," he said.
"We expect a full success of the 'Journey of Harmony', which will contribute to the promotion of the Olympic ideal as well as facilitate the mutual understanding and friendship between the Chinese and Argentine peoples," Liu Jingmin, executive vice-president of the Beijing Organizing Committee for the Games of the XXIX Olympiad (BOCOG), said at a reception organized by the Argentine city on Thursday evening.
Covering a total distance of 137,000 km, the Beijing Olympic Torch Relay has the longest route in the history of the relay.
Starting from Beijing, the relay winds across Asia, Europe, North and Latin America, Africa, Oceania, and then back to China before the torch ignites the cauldron at the opening ceremony of the Games on Aug 8.
